Use 'figment' for abstract or imaginary ideas, not physical objects that actually exist. Her perfect partner was a figment, no one could match that ideal.
Pro Tip 2/3
Negative Connotation
'Figment' often signals something falsely perceived or believed, without evidence. His claim of vast wealth was a figment, as he actually owed money.
Pro Tip 3/3
Expressing Disbelief
Use 'figment' to express skepticism about the reality of something mentioned. Are you sure you saw a ghost, or is that a figment of your imagination?